The surface acoustic wave (SAW) delay lines with (002)ZnO/IDT/SiO2/Si structure are fabricated by depositing (002)ZnO films and SiO2 films on Si substrate using RF magnetron sputtering method, meanwhile, the acoustic characteristics of Rayleigh wave generated by the (002)ZnO/IDT/SiO2/Si structure, including the phase velocity, electromechanical coupling coefficient, are studied theoretically by the 3D finite element method (FEM). And the experimental results well agree with the numerical results. The influence of the thickness of ZnO thin films on the Rayleigh wave properties is analyzed，it is found that the maximum electromechanical coupling coefficient k2 of 3.88% can be achieved when the thickness of ZnO film is 8 μm. At the same time, the properties of Rayleigh wave generated by the (110)ZnO/IDT/SiO2/Si structure are also analyzed. The results show that the maximum electromechanical coupling coefficient k2 of 5.5% can be achieved when the thickness of ZnO films is 8 μm.